[Info-vax] Reading Sequentially through an Indexed File...

[Stephen Hoffman]

On 2018-05-16 16:38:22 +0000, Doc Trins O'Grace said:

> On a OpenVMS V8.4 Itanium: with SET/RMS/QUERY=DISABLE; only doing $GETs 
> (with NLK+RRL bits set), on an indexed file... all other things being 
> equal. Are there any performance benefits to be garnered by opening the 
> file exclusively versus shared?

Replacing HDD with SSD is usually the big win, particularly in terms of 
the costs involved for the gains received.

Previous discussions and postings here in the comp.os.vms newsgroup can 
be a start for the probably-not-going-to-help-much RMS tuning.  But 
surprises do sometimes happen.  Hein is fond of his rms_tools on the 
freeware, maybe starting with rms_tune_check here.  There's the generic 
FDL performance tuning available with OpenVMS, and there's converting 
the existing contents into a new file, if those have not been performed 
recently.

It'll be more work to stop pretending that a descendent of a unit 
record card punch device design is ever going to be fast, and rework 
the app design away from small wads of data read and processed one hunk 
at a time.   That can involve a different backing store for the data 
and preferably one that supports big wads of data loaded into virtual 
memory, and that running in parallel with the data processing using KP 
threads or parallel processes or whatever, and that in parallel with 
big wads of data being written out in larger hunks or whatever the 
results of the processing might be.  (RMS tends to fall flat in a 
couple of areas, one of which is its fondness for having all data 
flushed to disk.  That's great and wonderful for data consistency, but 
stinks for performance, and there's a whole lot happening in many apps 
that doesn't need intermediate consistency.)

Another alternative to your own unmarshaling and marshalling code might 
be MariaDB or such, as various folks are finding newer databases much 
faster than RMS indexed files.
https://groups.google.com/d/msg/comp.os.vms/YNKQP5P1IJg/7FHK2ulABQAJ

Indexed file internal design, RMS performance:
https://groups.google.com/d/msg/comp.os.vms/qYfRGDUuQMo/MHJssXDAOhwJ
https://groups.google.com/d/msg/comp.os.vms/VZ_p2skKGIQ/AdyfI-z7BQAJ


-- 
Pure Personal Opinion | HoffmanLabs LLC